A printing apparatus such as a printer of the type widely used as an output terminal for a computer or the like performs printing by receiving data from the computer and driving a print head to form dots on a recording medium such as paper. When the history of printers is reviewed, we see that at the beginning, printers included a character generator that developed fonts, using which printing was carried out based on text data received from the computer, whereupon a function to receive and print image data was added as the graphics processing functions of computers increased and became more widely available.
The printing of image data can be realized in many different ways, but from the standpoint of ensuring that such printing capability can handle the wide range of data generated by computer application programs, a standard construction has been adopted in which data that is compatible with the characteristics of the print head and paper feeder used by the printer is generated by a printer driver installed in the computer, and this data is forwarded to the printer, whereupon printing is carried out. This type of printer driver generates dot data to be formed by the print head based on preset data already stored in the printer driver regarding the printer's resolution, color reproduction capability including the number of inks, print head nozzle construction (the number and pitch of the nozzles), paper feed precision and the like. For example, if a printer comprising a printing apparatus includes the low-density ink colors of light cyan (LC) and light magenta (LM) in addition to the ink colors of cyan (C), magenta (M), yellow (Y) and black (K), and the print head is an inkjet print head that can eject ink drops of three different sizes, the printer driver rasterizes image data received from an application program, performs color correction, and carries out halftoning to express images using ink drops of three sizes and six colors.
On the other hand, with the recent popularity of digital still cameras (so-called digital cameras), PDAs, cellular phones and other peripheral devices, the demand for printing of data from such devices without the need for a computer has increased. Because these peripheral devices are limited in terms of the processing capabilities of their internal CPU and the amount of installed memory, they cannot easily carry out their own processing for the rasterizing, color correction, halftoning and other processes described above. Accordingly, a printing apparatus has been proposed wherein a module that performs such processes as rasterizing, color correction and halftoning is incorporated in the printer such that image data received from the peripheral device in JPEG or other format is processed within the printer before it is printed by the printer. As in the prior art, such a printing apparatus can also be connected to a computer for printing. Therefore, this type of printing apparatus can carry out printing using received print data that has already undergone image processing by the computer as well as printing using received raw image data that subsequently undergoes processing by the printer. The latter type of printing is called direct printing.
A printing apparatus that carries out these multiple printing processes includes multiple interfaces to enable communication with users, computers, peripheral devices and other external components and carry out exchange of information such as input of information pertaining to printing apparatus operating instructions and output of status information regarding the operating state of the printing apparatus to and from external devices via these multiple interfaces. This status information output to the user may be made using text or graphics displayed on a liquid crystal panel or via a voice message emitted from a speaker, and such output to a computer may be made in the form of data transmission over electrical signals.